When a prospect says something like, "well, at this point, our decision really comes down to build versus buy", don't fear, you've already won most of the battle.
Your prospect has recognized that they need a product like yours and that they have to act. Getting a prospect to act -- and act quickly -- is the hardest part of selling innovation.

That said, you still have to address the issue.

I've always believed that the best way to address this concern isn't to give an opinion or a pitch; instead, the best approach is to give the prospect some topical things to consider as they look to make a decision. You're an expert in this area, you know lots of stuff that they don't. Help them think it through.

Here are five things you can encourage them to consider.

1. Specialization -- the world is complicated, companies need to focus on what they do well. Your prospect is good at their business and you're good at your business. Is it worth it for them to deviate from what they do well to try doing what you do well? Could that energy and those resources be better utilized on their core business? As Peter Drucker said, "do what you do best, and outsource the rest."

2. Unintended costs -- project and product managers know that when they begin a new project they don't know what they don't know. There are always unintended costs, requirements, hurdles and delays that come up when pursuing a new venture. It can be helpful to lay out, based on your own experience, what some of those unintended costs might be as your prospect sets out on building it themselves. Give examples. Highlight some of the things you've learned yourself.

3. Leverage with vendors -- because your prospect would be building the product for just one client (themselves) there are no economies of scale and little leverage with vendors. The costs could be far greater than they might think. List some vendors where this might apply.

4. Risk -- in my experience, when a company is considering building something themselves, they generally don't believe that the thing that they're looking to build is all that important. They'd admit that they might not do it as well as an expert but, "what's the big deal?" It's worth having a few ideas about what might make it a big deal if your prospect doesn't build it well; e.g. "if you don't want to be very high quality in this area, that's ok, but here are some potential consequences."

5. Experience -- over the last few years I've interviewed lots of consultants at top consulting firms. I always push them on describing why they're valuable. That is, how do they justify going into a business that they know nothing about to people there what to do? The answer is the same every time: "experience". They've worked on similar problems with similar companies in similar industries. They've been through it before. The same thing exists in 'build versus buy'. If you're really good at what you do, it's generally not because you hit a few home runs, it's usually because you've done all of the little things over the years, learned some tough lessons and iterated to make the product better. Your prospect is going to have to go through that pain too. Is it worth it?

As Drucker says in the quote above, if a project deviates from a company's core mission, it's generally best to outsource it. Pushing a prospect to consider these five things not only positions you as a thoughtful expert but it also helps screen out clients that aren't a good fit.

That said, be sincerely open to the fact that building might be the right thing for your prospect. So don't "tell" them, help "guide" them. If after considering each of these factors your prospect still decides to build it themselves, that's a good outcome. It truly is. It means that they don't value the uniqueness of your mission or product offering and likely won't make a great partner down the road. There's nothing wrong with that.

When a prospect is considering build versus buy, raise the five issues above. You'll typically find that the way your prospect addresses these concerns will either help them see your value more clearly or will help you screen out a partner that isn't a great fit.